Supplemental fuel feed system for internal combustion engines



Filed April 4, 1961 July 9, 1963 l'/ m w INVENTOR COQDoA/H. M/LLAR.

BY Mu MM ATTORNEY United States Patent Ofi" 3,096,751 Patented July 9, 1963 3,896,751 SUPPLEMENTAL FUEL FEED SYSTEM FQR INTERNAL COMBUSTION ENGINES Gordon H. Millar, Mound, Minn, assignor to McCulloch Corporation, Scott Division, Minneapolis, Minn, a corporation of Minnesota Filed Apr. 4, 1961, Ser. No. 100,657 2 Claims. (Cl. 12.3-119) This invention relates to fuel feed systems: and more particularly to a fuel system including means for supplying additional fuel to the combustion chamber of an internal combustion engine during rapid acceleration of the engine.

The invention will be described by way of example in combination with a two-cycle outboard motor.

When an outboard motor is used to pull a heavy load such as a water skier or another boat, the acceleration of the motor in response to a rapid advance of the throttle is often unsatisfactory. With such a load attached to the boat, the motor will often tend to slow down momentarily as the throttle is rapidly advanced. This undesirable delay in motor acceleration results partially from the necessity inherent in may two-cycle motors to pass the fuel-air mixture through the crankcase before the mixture enters the combustion chamber. This delay in acceleration response at the time the throttle is rapidly advanced will thus often cause the motor to decelerate momentarily just at the time additional power is most needed.

Another shortcoming of conventional fuel feed systems is that the fuel-air mixture will often become excessively lean at the time the throttle is rapidly advanced. It is well known that a lean mixture can cause severe overheating of the engine. Occasionally overheating in an outboard motor caused by a lean fuel mixture will result in melting or burning out of a piston. This is especially true when a mechanical spark advance is used.

It has been previously shown that supplemental fuel can be introduced directly into the intake manifold of an internal combustion engine for the purpose of priming or facilitating starting of the engine. For operation, these previous devices depend for the most part on flooding of the carburetor, certain pressure conditions in the intake manifold or the like and do not provide the advantages of the present invention.

It is accordingly an object of the present invention to provide an improved fuel feed system which will allow immediate engine response to a rapid advance of the throttle.

It is still a further object of this invention to provide and improved means for reliably preventing a lean mixture during rapid acceleration of the motor.

It is yet another object of this invention to provide an improved supplemental fuel feed system for an internal combustion engine which supplies supplemental fuel to the engine when the throttle is rapidly advanced but not when the throttle is advanced slowly.

It is still a further object of this invention to provide an improved fuel feed system of the type described which is economical to construct, reliable in operation and requires relatively few additional parts.

Briefly stated, the present invention provides an improved fuel feed system for an internal combustion engine including means operatively connected to the throttle for forcing fuel directly through a nozzle positioned adjacent to the intake port and into the intake manifold of the engine whereby a stream of fuel substantially unmixed with air is introduced directly into the cylinder in response to a rapid opening of the throttle.

These and other more detailed and specific objects will be disclosed in the course of the following specification,

reference being had to the accompanying drawing, in which- The FIGURE is a side elevation of a two-cycle outboard motor and carburetor partially in section.

Referring now to the figure there is shown a two-cycle outboard motor 10 for use in driving a boat through the water and including a crankcase 12, a cylinder 14, a water cooling jacket 16, crankshaft 17 and piston 18. Attached to an intake pipe 20 which communicates with the crankcase 12 in the usual manner is a carburetor 22.

The cylinder 14 is provided with a pair of integral longitudinally extending flanges 24 and 26 at the right of the cylinder as shown in the figure. Attached to the ends of flanges 24 and 26 is an intake bypass cover 28. The opening 30 between the cover 28 and cylinder 14 comprises an intake bypass duct communicating at one end with the crankcase 12 in the usual way and also with an intake port 32 provided in the wall of the cylinder 14. At the left side of the cylinder 14, as shown in the figure, there is a pair of longitudinally extending flanges 34 and 36. Secured to each of the flanges is an exhaust cover plate 38. The exhaust cover plate 38 has an exhaust pipe 40 integral therewith. Between the cover 38 and cylinder wall 14 is an exhaust passage 42 which communicates through an exhaust port 44 with the cylinder chamber 46.

The carburetor 22 includes the usual air inlet 50 and air outlet 52 which, as mentioned above, is connected in the usual way to the intake pipe 20. The carburetor 22 also is provided with a conventional float chamber 54 which serves as a fuel storage means and a float 56.

Fuel is supplied from a fuel storage tank (not shown) to the carburetor through fuel line 58. The carburetor is provided with a conventional throttle butterfly valve 60 pivotally mounted on a pivot 61. A throttle control lever 62 is secured to pivot 61 for controlling the fuel-air mixture and the speed of the motor in the usual way. The throttle butterfly valve 66 is operated by a throttle line 64 which is secured to the throttle control lever 62. Thus, by moving the throttle line 64 to the left the control lever 62 will cause the butterfly valve 66 to pivot counterclockwise as shown in the figure about the pivot 61, thereby closing the throttle. Clockwise movement of the control lever 62 will, of course, open valve 60. Integral with the control lever 62 is a supplemental fuel pump control lever 66. Lever 66 is provided with an opening 68 therein extending radially from the pivot 61. Operatively connected to the supplemental fuel pump contnol lever 66 and throttle control 64 is a connecting rod 72 and pump piston 70 attached to the lower end of rod 72. The connecting rod 72 is provided with a transversely extending pin 74 which fits in the opening 68 of the pump control lever 66. The piston 70 is, in this way, operatively connected to the pump control lever and throttle control line 64.

The piston 70 is slidably mounted in a cylindrical opening 76 formed in the body of the carburetor 22. The upper end of the cylinder 76 is closed by means of a suitable plug 78 threaded into the top of cylinder 76. Plug 78 is provided with a central opening 80 through which passes the connecting rod 7 2. The lower end of the cylinder 76 communicates with the float chamber 54 by means of a port 82. The port 82 is provided with an enlarged diameter at 83 having a ball 84 therein. The ball 84 will seat against annular valve seat 81 under certain conditions to act as a check valve which allows the flow of fluid from the float chamber 54 into the pump cylinder 76 'but prevents flow of fuel in the reverse direction. The ball 84 can be held movably in the port 82 by a suitable retainer ring 85.

The pump chamber 76 is provided at the bottom with an outlet port 86 which communicates through a suitable filBl supply line 88 with the supplemental fuel supply nozz e 90.

A fuel supply nozzle 90 comprises threaded nozzle member 92 which is screw threaded into a suitable threaded opening 94 in the intake bypass cover 28. The nozzle 92 is provided with a longitudinal bore 96 communicating at one end with the intake bypass chamber 30 and at the other end with the supplemental fuel supply line 88. I

The nozzle 90 may be, if desired, provided with a constriction 98 at the end thereof projecting into the intake bypass 30. The provision for constriction 98 at the nozzle opening will assist in breaking down the fuel passing into the cylinder from the nozzle to relatively small size droplets. The requirement for a constriction 98 will depend upon a number of factors such as the diameter and length of passage 96, the size of the engine and the type of fuel used.

Secured to the nozzle 90 by threads 100 is an adapter 102 having a relatively large bore at 104 communicating with a relatively small bore 106. A ball 108 provided in the adapter 102 acts as a check valve to ensure flow of fuel from the carburetor into the intake manifold and to prevent flow in the reverse direction. A spring 118 positioned between the ball 108 and nozzle 90 maintains the ball 108 in the normally seated position against an annular seat 107. The fuel supply line 88 may be secured to the adapter 102 and to the outlet port 86 by suitable clamps 112 and 114.

The operation of the invention will now be described. During relatively constant speed operation of the motor, the throttle control line 64 will move the butterfly valve 60, control levers 62 and 66 and the accelerator pump piston 70 from one position to another relatively slowly. Thus, as the operator accelerates the motor slowly, the throttle line 64, control lever 62, butterfly valve 60 and supplemental fuel control lever 66 will move slowly in a clockwise direction about pivot 61 and the piston 70 will simultaneously move slowly toward the lower end of the cylinder 76. As the piston 70 is slowly depressed, the check valve ball 84 is held by gravity off the seat 81 as shown in the figure. Ball 84 will not be forced against the seat 81 under these conditions because of the relatively slow flow of fuel over the valve seat 81 in port 82, thereby allowing fuel to pass from the cylinder 76 through port 82 and into the float chamber 54. The fuel will not pass through adapter 102 into nozzle 90 under these conditions because the pressure of spring 100 holds ball 108 in a seated position.

When, however, the throttle control line 64 is moved rapidly to the right in the figure, the butterfly valve 60, control lever 62 and pump control lever 66 will pivot rapidly in a clockwise direction about the pivot 61. As a result, the pump vpiston 70 will be rapidly depressed. The relatively rapid flow of fuel to the float chamber through port 82 will force the check valve ball 84 against the seat 81 and cause an increase in pressure in cylinder 76 and line 88.

As the piston continues to move downwardly the fuel moving into line 88 will unseat the ball 108 and pass through nozzle 90 into chamber 30. The check valve formed by ball 84 and seat 81 thus comprises a means for permitting supplemental fuel flow through the nozzle 90 upon rapid movement of the throttle to the open position.

The adapter 102,, ball 108 and spring 110 thus oompnise a first valve adapted to open at a first pressure within the line 88 and cylinder 76. The seat 81 and ball 84 comprises a second valve adapted to close at a lower pressure. As the piston 70 begins to move rapidly downward, spring 110 will continue to hold ball 108 in the seated position thereby causing a pressure increase in cylinder 76 sufficient to seat ball 84. After ball 84 is seated, continued pressure increase within cylinder 76 and line 88 will force the second valve to the open position allowing fuel to pass through nozzle 90'. The rapid downward movement of the piston 7 is in this way able to close the second valve and open the first valve.

The rapid flow of fuel through nozzle results in a momentary stream 128 of raw fuel through the intake port 32 and directly into the cylinder chamber 46. It will be understood, however, that the intake timing of the normal fuel-air mixture'supplied through the intake bypass chamber 38 as well as the streams of raw fuel will be controlled by the movement of the piston 18 downwardly beyond the intake port 32 in the usual manner. Thus, during the intervals in the cycle of operation in which port 32 is open, the stream of supplemental fuel 120 will pass directly into the cylinder.

When the throttle control line 64 is moved to the left in the figure, the throttle parts 62 and 66 pivot clockwise about pivot 61 thereby elevating the piston 70. When the piston 78 is elevated, the check valve 84 is again moved away from the seat 81 thereby allowing fuel to be drawn into the accelerator pump chamber 76 from float chamber 54 through port 82. In this way, the fuel supply in the accelerator pump chamber 76 is replenished.

The present invention, although it is relatively simple in construction and economical to manufacture, successfully provides a rapid and immediate increase in engine speed as the throttle is rapidly opened. The rapid acceleration response is especially important when the engine is heavily loaded. Furthermore, the rich mixture resulting from supplemental streams of fuel 120 supplied directly to the cylinder chamber prevents excessively lean mixtures as the'engine accelerates, thereby reducing overheating and consequent damage to engine parts. The invention also permits the introduction of supplemental fuel into the engine only when the throttle is advanced rapidly and not during relatively slow acceleration thereby reducing fuel consumption and increasing economy of operation.

It is to be understood that suitable modifications may be made in the structure as disclosed, provided such modifications come within the spirit and scope of the appended claims. Having now therefore fully illustrated and described my invention, what I claim to be new and desire to protect by Letters Patent is: a 1. In a two \cycle internal combustion engine having a fuel supply, a cylinder, a piston slidably mounted therein and a crankcase the combination comprising a fuel feed system including a carburetor, a throttle valve in said carburetor, an inlet pipe leadingfrom said carburetor to said crankcase, a bypass duct leading from said crankcase to said cylinder, said cylinder having an inlet port in the side wall thereof communicating with said bypass duct, a fuel' pump chamber communicating with said fuel supply, a fuel duct communicating with said' chamber, a plunger communicating with said chamber, said plunger being operatively connected to throttle valve to expel fuel from said chamber through said duct when said throttle is opened, a check valve between said fuel supply and said chamber, a supplemental fuel nozzle rigidly mounted inthe wall of said bypass duct on an axisextending through said inlet port, said nozzle being positioned to direct a stream of fuel into said bypass duct and through said inlet port, said stream thereby passing directly into said cylinder when said piston moves out of sealing engagement with said inlet port, said nozzle communicating with said fuel duct, a pressure responsive valve means between the nozzle and the chamber to permit the flow of fuel from said chamber through said pressure responsive valve only when the pressure within said chamber has exceeded a predetermined value, said fuel being thereby fed continuously from said carburetor through said inlet duct into said crankcase and bypass duct and directed in a stream from said nozzle into said cylinder only when the throttle valve is opened.

2. In a supplemental fuel feed system for a two-cycle internal combustion engine with a cylinder, an engine piston slidably mounted therein and a crankcase, the combination of a carburetor, an intake pipe connected between said carburetor and said crankcase, an inlet port in the side of said cylinder, a bypass duct communicating between said crankcase and said inlet port, a fuel storage means, a throttle valve in said carburetor, a throttle control means operatively connected with said throttle, said carburetor having a cylindrical pump chamber therein and a float chamber, a pump piston slidably mounted within said pump chamber, an actuator rod connected to said pump piston, said actuator rod projecting outwardly from said carburetor and being operatively connected to said throttle control means, said carburetor having a port communicating between said float chamber and said pump chamber, a check valve in said port to prevent flow from said pump chamber to said float chamber, said check valve being adapted to close only when said throttle valve is opened rapidly and being adapted to remain open when said throttle valve is opened slowly, a supplemental fuel nozzle rigidly secured to said bypass References Cited in the file of this patent UNITED STATES PATENTS Viel Sept. 7, 1937 Stanly Apr. 4, 1950 

1. IN A TWO CYCLE INTERNAL COMBUSTION ENGINE HAVING A FUEL SUPPLY, A CYLINDER, A PISTON SLIDABLY MOUNTED THEREIN AND A CRANKCASE THE COMBINATION COMPRISING A FUEL FEED SYSTEM INCLUDING A CARBURETOR, A THROTTLE VALVE IN SAID CARBURETOR, AN INLET PIPE LEADING FRON SAID CARBURETOR TO SAID CRANKCASE, A BYPASS DUCT LEADING FROM SAID CRANKCASE TO SAID CYLINDER, SAID CYLINDER HAVING AN INLET PORT IN THE SIDE WALL THEREOF COMMUNICATING WITH SAID BYPASS DUCT, A FUEL PUMP CHAMBER COMMUNICATION WITH SAID FUEL SUPPLY, A FUEL DUCT OMMUNICATION WOTH SAID CHAMBER, A PLUNGER COMMUNICATION WITH SAID CHAMBER, SAID PLUNGER BEING OPERATIVELY CONNECTED TO THROTTLE VALVE TO EXPEL FUEL DIRECT A STREAM OPF FUEL INTO SAID BYPASS DUCT AND THROUGH IS OPENED, A CHECK VALVE BETWEEN SAID FUEL SUPPLY AND SAID CHAMBER, A SUPPLEMENTAL FUEL NOZZLE RIGIDLY MOUNTED IN THE WALL OF SAID BYPASS DUCT ON AN AXIS EXTENDING THROUGH SAID INLET PORT, SAID NOZZLE BEING POSITINED TO DIRECT A STREAM OF FUEL INTO SAID BYPASS DUCT AND THROUGH SAID INLET PORT, SAID STREAM THEREBY PASSING DIRECTLY INTO SAID CYLINDER WHEN SAIS POSTON MOVES OUT OF SEALING ENGAGEMENT WITH SAID INLET PORT, SAID NOZZLE COMMUNICATING WITH SAID FUEL DUCT, A PRESSURE RESPONSIVE VALVE MEANS BETWEEN THE NOZZLE AND THE CHAMBER TO PERMIT THE FLOW OF FUEL FROM SAID CHAMBER THROUGH SAID PRESSURE RESPONSIVE VALVE ONLY WHEN THE PRESSURE WITHIN SAID CHAMBER HAS EXCEEDED A PREDETERMINED VALUE, SAID FUEL BEING THEREBY FED CONTINUOUSLY FROM SAID CARBURETOR THROUGH SAID INLET DUCT INTO SAID CRANKCASE AND BYPASS DICT AND DIRECT IN A STREAM FROM SAID NOZZLE INTO SAID CYLINDER ONLY WHEN THE THROTTLE VALVE IS OPENED. 